1. Field of Invention
This invention relates to adiabatic expansion refrigeration systems and in particular to air conditioning systems having a readily accessible source of low-grade heat, such as in an automobile.
Typical air conditioning refrigeration systems for automotive applications employ mechanical compressors to convert low-pressure vapor to high-pressure vapor in a closed refrigeration circuit and which employ adiabatic expansion and condensation to extract heat from the environment of the passenger compartment. The mechanical refrigeration circuit comprises a mechanical compressor, a vapor condenser and an evaporator or a refrigeration unit in a heat exchanger. In systems such as an automobile air conditioning system considerable power is expended in order to drive the compressor. The power is derived from the mechanical output of the internal combustion engine which increases the fuel consumption and may cause the engine to overheat. What is needed is an air conditioning system which does not waste fuel or cause excessive heating.
2. Description of the Prior Art
Absorption-type refrigeration systems are known which employ a heat source and highly endothermic reactants such as halide salts in water as heat absorption media. Such refrigeration systems operate on a principle of heat absorption by heat exchange with the environment upon contact with endothermic reaction products. The reactants involved in the endothermic reaction are typically separated by heating for recycling. Any substances having high endothermic affinity for one another and which can be separated by heating may in theory be used in an absorption refrigeration system.
Also well-known are ammonia-absorption refrigeration cycle systems in which ammonia vapor is absorbed and extracted from ammonia solution. Ammonia-absorption systems are justified only in cases where a suitable source of heat is available which would otherwise be wasted. Ammonia is also known for use in adiabatic expansion refrigeration systems. All of these systems have been suggested for automotive applications.
The following patents were uncovered in a review of prior art refrigeration systems:
Tsunesuke Kubo et al., U.S. Pat. No. 3,077,083 issued Feb. 12, 1963;
Pippert, U.S. Pat. No. 3,153,441 issued Oct. 20, 1964;
Hess, Jr., U.S. Pat. No. 3,230,731 issued Jan. 25, 1966; and
Eannarino et al., U.S. Pat. No. 3,535,888 issued Oct. 27, 1970.
The known prior art suggests the use of absorption-type air conditioning systems in connection with automotive applications where there is a source of heat available which might otherwise be wasted. While the prior art suggests elimination of mechanical compressors, nothing is suggested which would be a suitable substitute for a mechanical compressor in an adiabatic expansion refrigeration system.